Overexpression of human release factor 1 alone has an antisuppressor effect in human cells.

摘要: Two eukaryotic proteins involved in translation termination have recently been characterized vitro experiments. Eukaryotic release factor 1 (eRF1) catalyzes the of polypeptide chain without any stop codon specificity. The GTP-binding protein eRF3 confers GTP dependence to process and stimulates eRF1 activity. We used tRNA-mediated nonsense suppression at different codons a cat reporter gene analyze activities human overexpressed cells. In chloramphenicol acetyltransferase assay, we measured competition between suppressor tRNA factors when was present ribosomal A site. Whatever (UAA, UAG, or UGA) open reading frame, overexpression alone markedly decreased translational readthrough by tRNA. Thus, like procaryotic RF1 RF2 Escherichia coli, seems an intrinsic antisuppressor activity Levels antisuppression both were almost same as those alone, suggesting that eRF1-eRF3 complex-mediated may be controlled expression level eRF1. Surprisingly, had inhibitory effect on expression. results mRNA stability studies suggest inhibits transcriptional level. This indicates vivo, perform other functions, including stimulation